DE2109841C3 - Photographic camera with an electronic time forming device - Google Patents

Description

The invention relates to a photographic camera with an electronic time-forming device, activated by a mechanical switch operated by the closing mechanism will.

Such cameras are known in various embodiments. They are used for the operation of the electronic timing device generally used mechanical switches usually have Contact springs that tend to Pre'len when the switch is operated, which leads to irregularities in terms of the effective contact and thus the electronic timing leads, whereby the functional reliability is significantly impaired in the preparation process. About the disadvantages of bouncing contact arrangements to fix, it is known from DE AS 17 72 237 that in a photographic camera with a electronic timing device that comes into operation at a predetermined point in time, which is determined by a electronic, by means of an impulse put into operation Schaller is determined, the electrical Impulse is generated in a manner known per se by a barrier and that the barrier is in front of one Function start with a predetermined speed running member is influenced, with a photoelectric or magnetic or capacitive barrier can be used. But now there are such barriers as precision components, not only complex and expensive in terms of production, but also dimensioned in such a way that that even with optimal design, their placement in the device, z. B. in the lock housing, due to lack of space not infrequently encounters serious difficulties. In addition, with regard to the influencing the barrier, with Predetermined speed running member naturally be expected with wear, the one means increasing uncertainty factor for the time calculation with the service life of the camera.

The object of the invention is to identify such deficiencies in cameras of the type specified at the outset easy way to eliminate and without moving parts to achieve with certainty that the electronic timing device always comes into operation at the same switching time and at the Timing irregularities are excluded.

The solution to the problem is achieved in that the mechanical switch is an electronic one The bistable toggle element controls the welcnes from its one switching state to the first contact the other switching state changes and the electronic time-forming device is triggered by an electrical impulse in function

Although it is known from DE-PS 12 47 845 a device that has a control device for setting

ίο has an aperture in the one by hand Adjustable resistance in a bridge circuit affects a switch so that only during the Transition of the manual adjuster from a marked position to an adjacent power source with a electronic switching device is connected.

The switch in question is, however, arbitrarily manual regardless of the triggering of the camera can be switched on and therefore with the switch according to the invention, which is inevitably removed from the closing element is operated, not comparable.

The task of the known device also differs considerably from that of the subject matter of the invention away. While the subject matter described in DT-PS 12 47 845 is the basis for the task is to automatically switch off a power source after the completion of a control process, it is the problem division of the subject of the invention, for a time-forming device the constancy of the When the shutter speed setting is switched on

jo ges as well as the constancy of the duration of each particular to ensure formed shutter speed.

The subject matter of the invention is explained below using the description of an exemplary embodiment. The electronics are connected to the battery 21 in a known manner by a switch 20 actuated by the trigger connected. The bistable flip-flop is in this embodiment as a flip-flop with the transistors 1 and 2 and resistors 3 to 8 are formed. The capacitor 10 ensures that the Flip-flop after switching on the switch 20 toggles into a predetermined switching state in which transistor 1 is blocked and transistor 2 is conductive.

If the shutter is now opened, it will

Flip-flop through the from a draining link of the

• '5 shutter operated switch 9 in the second Switching state tilted in which the transistor 1 is conductive and the transistor 2 is blocked. DaJurch receives the base of the transistor 14 via the capacitor 11 a positive pulse, whereby the transistor 14

w briefly becomes conductive and the time-forming capacitor 17 via resistor 15 contains.

The time can now be calculated in a known manner with the aid of a threshold circuit 18 by charging the Time formation capacitor 17 through the photoresistor

') 5 16 take place, and the closure by the magnet 19 to be closed again.

The circuit arrangement can also be integrated together with the threshold value circuit in a single one th circuit, whereby the

iiu structure significantly simplified.

1 sheet of drawings

Claims (1)

Claim: Photographic camera with an electronic time forming device operated by one of the expired closure actuated mechanical switch is put into function, thereby characterized in that the mechanical switch controls an electronic bistable toggle element, which at the first contact from its one switching state to the other switching state tilts and an electrical impulse causes the electronic time-forming device to function puts.